Discuss the relationship between data warehousing and OLAP.

What will be an ideal response?

In the past few years, relational DBMS vendors have targeted the data warehousing market
and have promoted their systems as tools for building data warehouses. A data warehouse
stores operational data and is expected to support a wide range of queries from the relatively
simple to the highly complex. However, the ability to answer particular queries is dependent
on the types of end-user access tools available for use on the data warehouse. General-purpose
tools such as reporting and query tools can easily support ‘who?’ and ‘what?’ questions about
past events. A typical query submitted directly to a data warehouse is: ‘What was the total
revenue for Scotland in the third quarter of 2001?’. In this section we focus on a tool that can
support more advanced queries, namely online analytical processing (OLAP).
While OLAP systems can easily answer ‘who?’ and ‘what?’ questions, it is their ability to
answer ‘what if?’ and ‘why?’ type questions that distinguish them from general-purpose query
tools. OLAP enables decision-making about future actions.